Synthesis of delta8,14-bisdehydrooestrone 3-ethers



United States Patent 3,317,566 SYNTHESIS OF A -BISDEHYDROOESTRONE S-ETHERS John Stanley Whitehurst, Exeter, David John Crispin, Ashburton, and Clive Beresford Challis Boyce, Kent, England, assignors to Aspro-Nicholas Limited, London, England, a British company No Drawing. Filed Nov. 1, 1963, Ser. No. 320,845 Claims priority, application Great Britain, Nov. 8, 1962, 42,182/ 62 20 Claims. (Cl. 260-3453) This invention is concerned with a new and improved synthesis of A -bisdehydrooestrone 3-ethers and certain novel intermediates therefor.

According to the present invention, there is provided a process which comprises subjecting to cyclising conditions a 5,6,7,8-tetrahydro-1-keto-4[(2'-m-oxyphenyl) ethylJ-indan-S-one compound of the general formula:

wherein R represents a hydrocarbon substituent such as an alkyl group, preferably a lower alkyl group and particularly methyl, or a lower aralkyl group, for example a phenylalkyl group such as benzyl, and R represents hydrogen or a hydrocarbon substituent such as a lower alkyl group, for example methyl, ethyl, n-propyl or iso propyl, or a lower aralkyl group to produce a A -bisdehydrooestrone compound of the general formula:

wherein R and R have the same meanings as defined above.

Cyclisation is advantageously effected by the action of a suitable acidic reagent, for example a solution of phosphorus pentoxide in phosphoric acid, for example by heating to a temperature of from 50 to 90 C. for up to one hour under an inert atmosphere, for example of nitrogen, conveniently using approximately equal weights of phosphorus pentoxide and syrupy phosphoric acid. Alternatively, warming in the presence of dilute hydrochloric acid in methanol or ethanol may be employed.

Any A -isomer formed in the case in which R, is hydrogen may be converted to the desired A compound by the action of a base.

The compounds of general Formula I are novel compounds and form a part of this invention. They may be made, in accordance with a preferred feature of the invention, by oxidation of the corresponding lp-hydroxy compounds, which are also novel compounds forming a part of this invention, for example with chromic acid, conveniently by the solution of an aqueous solution thereof to a solution of the lB-hydroxy compound in a watermiscible solvent.

3,317,566 Patented May 2, 1967 In accordance with a preferred feature of the invention, the requisite lfi-hydroxy compound, namely a 5,6,7,8-tetrahydro 16 hydroxy 4[(2'-m-oxyphenyl) ethyIJ-indan-S-one, is obtained by m-oxyphenethylation of an alkali metal enolate of a 5,6,7,8-tetrahydro-1flhydroxyindan-S-one of the general formula:

(III) wherein R has the meaning defined above, in which the 1,8-hydroxy group is protected, such as by etherification, for example the lB-tetrahydropyranyl ether, followed by removal of the protecting group by hydrolysis or otherwise. The required starting compounds (5,6,7,8-tetrahydro-l-fl-hydroxyindan-S-ones) of Formula III may be obtained by the method described by C. B. C. Boyce and J. S. Whitehurst, J. Chem. Soc., 1960, 4547.

An alkali metal enolate, preferably the potassium enolate, of the protected lfl-hydroxy compound may be made by reacting it with an alkali metal or suitable alkali metal compound in a suitable solvent such as benzene or, preferably, t-butanol. Suitable alkali metal compounds which may be usedin place of potassium metal to make the potassium enolate are potassium hydride, potassium amide and potassium triphenylmethyl. Enol formation is preferably elfected in an inert atmosphere, for example of dry nitrogen, under reflux conditions.

The alkali metal enolate is m-oxyphenenthylated, for example m-methoxyphenethyl'ated, by reaction, conveniently in the same reaction medium without isolation and advantageously under reflux conditions, with a suitable 2-m-oxyphenethylating agent such as a 2-m-oxyphenylethyl toluene-p-sulphonate (obtainable from the corresponding 2-m-oxyphenylethyl alcohol by reaction with toluene-p-sulphonyl chloride) or a 2-m-oxyphenylethyl methanesu-lfon ate or, preferably, a 2-m-oxyphenylethyl p-nitrobenzenesulphonate (obtainable from the corresponding 2-m-oxyphenylethy1 alcohol by reaction with p-nitrobenzenesulphonyl chloride). It will be understood that the group in the meta-position of the m-oxyphenylating agent is the group R0 wherein R has the meaning defined above.

It is a particular feature of this aspect of the invention to carry out enolate formation and its aralykylation in t-butanol as use of this solvent raises the yield considerably with respect to that obtainable when using a solvent such as benzene, as may be seen by comparing Example 2 with Example 1.

The group protecting the lfi-hydroxy group, for example a tetrahydropyranyl ether group, is then removed, preferably without isolation of the protected compound, and this may be effected by hydrolysis by warming gently with a dilute aqueous alcoholic solution of a strong acid such as hydrochloric acid.

The resulting LB-hydroxy compound is then normally recovered by diluting the reaction mixture with water, extracting with a suitable solvent such as ether, evaporation of the solvent, and purification of the residual gum, as by chromatography. The lfl-hydroxy compound is then oxidised to the l-keto compound of Formula I as described above.

In the most typical case of the processes of the present invention both R and R represent methyl groups, and it will be understood that these groups remain constant throughout the successive stages outlined above.

In a narrow aspect, therefore, the present invention provides a process for making a A -bisdehydrooestrone compound which comprises cyclising with phosphorus pentoxide dissolved in phosphoric acid the compound obtainable by (a) treating 5,6,7,8-tetrahydro-Its-tetrahydropyranyloxy-8-methylindan-5-one first with potassium (or potassium hydride or potassium triphenylmethyl) in benzene and then (b) with 2-(m-methoxyphenyl)ethyl toluene-p-sulphonate, then (c) hydrolysing the product with aqueous hydrochloric acid and thereafter (d) oxidising the product with chromic acid.

A -bisdehydrooestrone compounds of general Formula II made in accordance with the present invention are useful intermediates for the manufacture of various steroid hormones, particularly 19-norsteroids. Thus, for example, the compound in which both R and R represent methyl groups may be converted to d,l-oestrone methyl ether as described in Chemistry and Industry (London), 1022 (1960).

The following examples illustrate the present invention:

EXAMPLE 1 1st stage A mixture of 5,6,7,8-tetrahydro-1fl-hydroxy-8-methylindan--one (III; R =CH (4 g.), dihydropyran (15 ml., distilled from potash), ether ml.) and concentrated hydrochloric acid (8 drops) was shaken mechanically for four hours at room temperature. More ether (ca. 50 ml.) was added and the solution was then washed with 10% potassium hydroxide solution, then water, and finally dried over MgSO Evaporation of the ether left the crude 5,6,7,8-tetrahydro-1ti-tetrahydropyranyloxy-8- methylindan-S-one (5.8 g.) which was sufficiently pure for the subsequent steps. The pure compound distilled at 130 C./0.05 mm., 11 1.5 150, A 242 mg, 610,800; x,,,,,, (film) 1663, 1447, 1337, 1254, 1201, 1126, 1074, 1033, 1020, 968, 906, 872 cm.-

2nd stage The crude lfi-tetrahydropyranyl ether (3 g.) in benzene (8 ml.) was converted into its potassium enolate by adding it to a mechanically stirred suspension of potassium (0.52 g.), potassium amide (0.66 g.) or potassium triphenylmethyl (3.40 g.) in benzene under dry nitrogen and refluxing the mixture gently for two hours.

3rd stage To the boiling solution of the potassium enolate 2-rnmethoxyphenylethyl toluene-p-sulphonate (3.80 g.) in benzene (8 ml.) was added over one hour and, after a further 12 hours, all solvent was evaporated to leave a residue containing 5,6,7,8-tetrahydro-LB-tetrahydropyranyloxy 4[2'-m-methoxyphenyl)ethyl]-8-methylindan-5- one.

4th stage The residue was warmed gently with 2 N hydrochloric acid (15 ml.) and ethanol (50 ml.) to hydrolyse the 15- ether group. Dilution with water, extraction with ether and evaporation of solvent left a gum which was chromatographed on neutral alumina (Grade I) to give colourless needles of 5,6,7,8 tetrahydro 113 hydroxy- 4[(2'-m-methoxyphenyl)ethyl] 8 methylindan-S-one (0.65 g., M.P. 88 C. from ether-petroleum spirit), k 249 my, 66000; (KBr disc) 3440, 1666, 1587, 1490, 1460, 1445, 1365, 1254, 1190, 1150, 1030, 885 cmr 5th. stage This compound (0.50 g.) dissolved in pure acetone (40 ml.) was treated dropwise with 8 N chromic acid until an orange-brown colour persisted. Ten minutes later saturated brine was added and the solution then extracted with ether. Drying over MgSO and evaporation of the solvent left a viscous gum. It was purified by chromatography of its benzene solution on Florisil whereby 5,6,7,8 tetrahydro 1 keto-4[(2'-m-methoxyphenyl) 4 ethyl]-8-methylindan-5-one (I; R=CH R =CH was obtained as a colourless gum (0.42 g.), a 250 m E7000; 'y (liquid film) 2934, 174 0, 1650, 1590, 1452, 1358, 1318, 1258, 1170, 1120, 1056, 872, 792 cm.- The bis-2,4dinitrophenylhydrazone crystallised from chloroform as red micro-needles, M.P. 258-2595 C.,

6th stage The compound I, where R=CH and R =CH (0.32 g.) was treated with a mixture of phosphorus pentoxide (2 g.) and syrupy phosphoric acid (1.6 ml.) at 75 C. under nitrogen for 20 minutes. After cooling and adding ice-water the organic material was extracted with etherethyl acetate (1:1). Evaporation, followed by chromatography of the product on Florisil, gave colourless needles of N -bisdehydrooestrone 3-methyl ether (II; R=CH R =CH (0.14 g., M.P. 108.5 C., x,,,,,,, 313 mu, 32,200; 7mm (KBr disc) 2877, 1720, 1585, 1548, 1482, 1416, 1278, 1242, 1134, 1034, 976, 863, 821, 805 cmf EXAMPLE 2 Example 1 is repeated, except that the second and third stages thereof are replaced by the following alternative procedures:

2nd stage The crude lfl-tetrahydropyranyl ether (3 g.) in tbutanol (60 ml.) was added slowly to a boiling and mechanically stirred solution of potassium (0.47 g.) in tbutanol (60 m1.) under nitrogen during 15 minutes and the solution refluxed for a further 30 minutes.

3rd stage To the boiling solution of the potassium enolate, 2-mmethoxyphenylethyl toluene-p-sulphonate (3.8 g.) in tbutanol ml.) was added dropwise during 3 hours. After a further 30 minutes refluxing, the solution was cooled, treated with water (200 ml.) and the t-butanol distilled off. The aqueous residue was extracted with ether, which was then dried and evaporated. The remaining oil Was partially distilled to remove a volatile fraction (B.P. 4550 C./ 0.05 mm.) and the residue was hydrolysed as described in stage 4 of Example 1. The yield of 5,6,7,8 tetrahydro 1B hydroxy-4[(2'-m-methoxyphenyl)ethyl]-8-methylindan-5-one was 0.82 g.

We claim:

1. A method of making a A bisdehydrooestrone compound which comprises subjecting a dione compound of the formula wherein R is selected from the class consisting of lower alkyl and lower aralkyl and R is selected from the class consisting of hydrogen, lower alkyl and lower aralkyl, to acidic conditions effective to cyclise the same to a fi -bisdehydrooestrone compound.

2. A method according to claim 1, wherein the dione is cyclised by reaction with phosphorus pentoxide in phosphoric acid.

3. A method according to claim 1, wherein the dione is cyclised by reaction in alkanolic solution with hydrochloric acid in the presence of water.

4. A method of making n -bisdehydrooestrone 3- methyl ether comprising subjecting 5,6,7,8-tetrahydro-1- keto 4[(2' m-methoxyphenyl)-ethyl]-8-methylindan-5- one to acidic conditions effective to cyclise the same to A wbisdehydrooestrone 3-methyl ether.

5. A method of making a dione compound of the formula 6. A method of making a 1,8-hydroxy compound of' the formula wherein R is selected from the class consisting of lower alkyl and lower aralkyl and R is selected from the class consisting of hydrogen, lower alkyl and lower aralkyl, comprising reacting an alkali metal enolate of a compound of the formula:

wherein R is selected from the class consisting of hydrogen and lower alkyl, the hydroxy group of which is protected by etherification with a protective ether group, with a 2-m-oxyphenethylating agent in which the mgroup has the formula R0 wherein R is selected from the class consisting of lower alkyl and lower aralkyl, and then hydrolysing ofi the protecting ether group.

7. A method according to claim 6, wherein the enolate is reacted with a 2-m-oxyphenylethyl-p-nitrobenzenesulphonate.

8. A method according to claim 6, wherein the enolate is reacted with a 2-m-oxyphenylethyl toluene-p-sulphonate.

9. A method according to claim 6, wherein the enolate is reacted with a 2-m-oxyphenylethyl methanesulphonate.

10. A method according to claim 6, wherein the enolate is reacted in solution in t-butanol.

11. A method according to claim 6, wherein the hydroxy group is protected by etherification with a tetrahydropyranyl group.

12. 5,6,7,8 tetrahydro 1,3-tetrahydropyranyloxy-4- [(2'-m-methoxyphenyl)ethyl]-8-methylindan-5-one.

13. 5,6,7,8 tetrahydro 1p -tetrahydropyranyloxy-S- methylindan-S-one.

14. A method of making A -bisdehydrooestrone 3- methyl ether comprising the successive steps of:

(a) etherifying the hydroxy group of 5,6,7,8-tetrahydro 1,B-hydroxy-8-methylindan-5-one with a protecting ether group;

(b) converting the etherified hydroxy compound to an alkali metal enolate thereof by reaction with an alkali metal enolating agent;

(c) reacting the enolate with an m-methoxyphenylethylating agent to form the corresponding 4-aralkylated compound;

(d) hydrolysing off the ether group protecting the 1;?- hydroxy group by the action of acid to form the corresponding 1fi-hydroxy-4-aralkyl compound;

(e) oxidising the 1fl-hydroxy-4-aralkyl compound by the action of chromic acid to the corresponding 1- keto-4-aralkyl compound;

(f) cyclising the 1-keto-4-aralkyl compound by the action of acidic conditions; and

(g) recovering the formed A -bisdehydrooestrone 3- methyl ether.

15. A method according to claim 14, wherein steps (b) and (c) are effected in t-butanol and the enolate is reacted with m-methoxyphenylethyl p nit'robenzenesulphonate.

16. A method according to claim 14, wherein step (b) the potassium enolate is formed by reaction with an enolating agent selected from the class consisting of potassium, potassium hydride, potassium amide and potassium triphenylmethyl.

17. Alkali metal enolates of 5,6,7,8-tetrahydro-lp-tetrahydropyranlyoxy-S-methyIindan-S-One.

18. The potassium enolate of 5,6,7,8-tetrahydro-l/3- tetrahydropyranyloxy-S-methyIindan-S-one.

19. A method of making a A -bisdehydrooestrone 3-(lower)alkyl ether comprising the successive steps of:

(a) oxidising with chromic acid a compound of the formula:

wherein R is lower alkyl and R is lower alkyl, to form the corresponding dione;

(b) cyclising the resulting dione by reaction with phosphorus pentoxide in phosphoric acid; and

(c) recovering the formed A -bisdehydrooestrone 3- (lower)alky1 ether.

20. A method of making a A -bisdehydrooestrone 3- (lower)a1kyl ether comprising the successive steps of:

(a) oxidising with chromic acid a compound of the formula:

wherein R is lower alkyl and R is lower alkyl, to form the corresponding dione;

(b) cyclising the resulting dione by reaction in alkanolic solution with hydrochloric acid in the presence of water; and

(0) recovering the formed A -bisdehydro0estr0ne 3- (lower) alkyl ether.

References Cited by the Examiner UNITED STATES PATENTS Johns 260-397.4 Ringold et a1. 260239.55 Ringold et a1. 260-3975 Sakakibara et a1. 260-397.3

FOREIGN PATENTS 3/1961 Belgium.

OTHER REFERENCES Crispin et 211., Proc. Chem. Soc., p. 356, November 1962.

Smith et aL, Experientia XIX/4, p. 177-178 (1963).

ELBERT L. ROBERTS, Primary Examiner. LEWIS GOTTS, Examiner. H. A. FRENCH, Assistant Examiner. 

1. A METHOD OF MAKING A $8.14 - BISDEHYDROOESTRONE COMPOUND WHICH COMPRISES SUBJECTING A DIONE COMPOUND OF THE FORMULA
 17. ALKALI METAL ENOLATES OF 5,6,7,8,-TETRAHYDRO-LB-TETRAHYDROPYRANLYOXY-8-METHYLINDAN-5-ONE. 